This invention relates generally to a method and apparatus for gas burners, and, more particularly, a method and apparatus for reduced circumference gas surface burner used in a gas-cooking product.
Atmospheric gas burners are commonly used as surface units in household gas cooking appliances. A significant factor in the performance of gas burners is their ability to withstand airflow disturbances from the surroundings, such as room drafts, rapid movement of cabinet doors, and oven door manipulation. Manipulation of the oven door is particularly troublesome because rapid openings and closings of the oven door often produce respective under-pressure and over-pressure conditions under the cook top.
These under-pressure and over-pressure conditions cause related pressure variations in the gas entering the burner chamber. Gas refers to any gas or fuel air mixture. The pressure variations can translate into flow disturbances at the burner ports causing flame extinction.
Some commercially available gas burners employ dedicated expansion chambers to attempt to improve stability performance. These expansion chambers are intended to dampen flow disturbances before such disturbances reach a respective stability flame. This damping is typically attempted by utilizing a large area expansion between an expansion chamber inlet and an expansion chamber exit, typically expanding by a factor of about ten. Accordingly, the velocity of a flow disturbance entering a burner throat is intended to be reduced by a factor of about ten prior to reaching a respective stability flame, thereby reducing the likelihood of flame extinction. Large area expansion and disturbance damping are not typically present in conventional main burner ports, making conventional main burner ports susceptible to flame extinction, especially at low burner input rates. Simmer stability is generally improved as the area expansion ratio is increased. If an expansion chamber inlet is sized too small, however, the gas entering an expansion chamber may be insufficient to sustain a stable flame at the expansion chamber port.
FIG. 1 illustrates an exemplary freestanding gas range 100 in which the herein described methods and apparatus may be practiced. Range 100 includes an outer body or cabinet 112 that incorporates a generally rectangular cook top 114. An oven, not shown, is positioned below cook top 114 and has a front-opening access door 116. A range backsplash 118 extends upward of a rear edge 120 of cook top 114 and contains various control selectors (not shown) for selecting operative features of heating elements for cook top 114 and the oven. It is contemplated that the herein described methods and apparatus is applicable, not only to cook tops which form the upper portion of a range, such as range 100, but to other forms of cook tops as well, such as, but not limited to, built in cook tops that are mounted to a kitchen counter. Therefore, gas range 100 is provided by way of illustration rather than limitation, and accordingly there is no intention to limit application of the herein described methods and apparatus to any particular appliance or cook top, such as range 100 or cook top 114.
Cook top 114 includes four gas fueled burner assemblies 200 which are positioned in spaced apart pairs positioned adjacent each side of cook top 114. Each pair of burner assemblies 200 is surrounded by a recessed area 124 of cook top 114. Recessed areas 124 are positioned below an upper surface 126 of cook top 114 and serve to catch any spills from cooking utensils (not shown in FIG. 1) being used with cook top 114. Each burner assembly 200 extends upwardly through an opening in recessed areas 124, and a grate 128 is positioned over each burner 200. Each grate 128 includes a flat surface thereon for supporting cooking vessels and utensils over burner assemblies 200 for cooking of meal preparations placed therein.
While, cook top 114 includes two pairs of grates 128 positioned over two pairs of burner assemblies 200 it is contemplated that greater or fewer numbers of grates could be employed with a greater or fewer number of burners without departing from the scope of the herein described methods and apparatus. Further, the burner assembly may rest directly on the cook top or within recesses.
Gas burners are subjected to pressure fluctuations both above the cook top on which they are mounted, as well as below. These pressures fluctuations can extinguish the flames of a burner when it is turned down to a very low setting. It is well known in the art that the addition of a stability chamber can improve stability at low flame settings. However, this concept requires the venturi tube to be located substantially adjacent to the inlet of the stability chamber. In traditional practice, the venturi is located in the center of round burners to provide uniform distribution of gas. Thus, the minimum diameter of the chamber of a burner that has a centrally located venturi and adjacent stability chamber can be approximated by the equation: Diameter of chamber=Diameter of venturi+2× radial length of stability chamber. Because the stability chamber requires a finite volume and length to function properly, a designer is often left with a burner diameter larger than desired in order to fit these features. Larger diameter burners are often not desired when space constraints, part cost, or efficiency demands are considered.
FIG. 2 is a side view of a known burner base. The width 164 of the burner body 150 is determined by the internal features, shown in FIG. 3. The height 162 provides height for the burner to be proximate to a grating (not shown) which, supports cooking vessels. The grating may be removeably attached to the burner body 150. Burner ports 154 are at the top of a wall 168 of the burner body. The wall 168 is generally annular and is formed about a central axis. Typically located above the burner ports is a burner cap (not shown). The burner cap closes the burner body 150 to create an internal chamber 156 such that the ports 154 and the stability chamber are the only exit for the gas during operation. The gas enters the burner body 150 through a venturi 152 from a burner throat 160 and accumulates in the chamber 156 before exiting the ports 154.
FIG. 3 is a top view of a known burner base 150 that can be used in a burner assembly for a gas range. Traditionally, the venturi 152 is located along the central axis 166 of a ring of burner ports 154. Stability chamber 160 is located to one side of the chamber 156 and opposite the stability chamber 160 is igniter mount 158 for mounting an electrode (not shown). The minimum diameter of the ring of ports is restricted by the size of the stability chamber 160 and the size of the venturi 152, and this is because the venturi 152 is located in the center of the burner.